Device for detecting a bend angle upon precisely bending a metallic pipe

ABSTRACT

A device for detecting a bend angle upon precisely bending a metallic pipe to be used in a method for bending a pipe in which precise bending is achieved by detecting a deviation of a distance between one point on said pipe to be bent and a fixed point outside of said pipe from another distance between a predetermined locus and said fixed point by means of an arm having its opposite end portions pivotably supported at said one point and said fixed point respectively, characterized in that there is provided means for detecting a sum of a rotational angle of said arm about said fixed point as the bending proceeds since the beginning of the bending work and an angular variation at the portion of said arm joined to said pipe to obtain a true bend angle.

United States Patent [191 Kubota e t al.

[ Sept. 17, 1974 [54] DEVICE FOR DETECTING A BEND ANGLE 3,570,292 3/1971 Steck et al. 72/173 3,661,002 5/1972 Peddinghaus 72/7 UPON PRECISELY BENDING A METALLIC 3,724,258 4/1973 Hofstede 72/342 PIPE Inventors: Saturn g g j Morikawa, Primary Examiner-Lowell A. Larson both of Hlroshlma, Japan Attorney, Agent, or Firm-Cushman, Darby & [73] Assignee: Mitsubishi Jukogyo Kabushiki Cushman Kaisha, Tokyo, Japan 22 Filed: Sept. 13, 1972 [57] ABSTRACT A device for detectmg a bend angle upon precisely [21] Appl' 288667 bending a metallic pipe to be used in a method for bending a pipe in which precise bending is achieved [52] US. Cl. 72/369, 72/30 by detecting a deviation of a distance between one [51] hilt. Cl B21d 7/14 point on said p p to be bent and a fixed point outside Fleld Of Search of Said from another distance between a p 72/ 173475 termined locus and said fixed point by means of an 33/174 N arm having its opposite end portions pivotably supported at said one point and said fixed point respec- [56] References cued tively, characterized in that there is provided means UNITED STATES PATENTS for detecting a sum of a rotational angle of said arm 2,870,817 1/1959 Boldrini 72/175 about said fixed point as the bending proceeds since 2,945,527 7/1960 Bower et a1 72/8 the beginning of the bending work and an angular var- 3,156,287 11/1964 Munro 72/8 iation at the portion of said am joined to aid to 3,339,392 9/1967 Buckwalter et al 72/166 Obtain a true b angle. 3,352,136 11/19 3? Clarke 72/8 3,406,551 10/1968 Coody 72/166 2 Claims, 3 Drawing Figures 3,459,018 8/1969 Miller 72/7 7 21,545,089 12/1970 Beckwell sg g w i 2 I 6 .2 5 o 0 4x 0 g 2 1 0 o 3 6 zzvfr/xrr/alv wFffZT/C DEVICE FOR DETECTING A BEND ANGLE UPON PRECISELY BENDING A METALLIC PIPE The present invention relates to a device for detecting a bend angle to be used in an apparatus for precisely bending a metallic pipe.

With regard to a method for precisely bending a metallic pipe, there has been proposed a method as illustrated in FIG. 1, which is described and claimed in the copending US. Pat. Application of Omori et al Ser. No. 289,212 filed Sept. 13, 1972. In this figure,'a deviation of a distance between one point B on a pipeA to be bent and a fixed point C outside of said pipe from another distance between a predetermined locus-and said fixed point C, is detected by means of an arm D having its opposite ends pivotably supported at said respective points B and C, and in accordance with the detected signal the forth and back movement of a press roll E is controlled to achieve precise bending. In such a case, normally the angle L0,, has been deemed as a bend angle. However, it has been found that in a actual bending work, the relation 46, 40 is not continuously true, in other words, the angle 40;, is continuously varying by a m nu m unt v t s. th bsrqiasw r One object of the present invention is, to provide a device for detecting a true bend angle upon precise bending in view of the above-referred disadvantage in the prior art. To this end, the invention provides a device for detecting a bend angle upon precisely bending a metallic pipe to be used in a method for bending a pipe in which precise bending is achieved by detecting a deviation of a distance between one point on said pipe to be bent and a fixed point outside of said pipe from another distance between a predetermined locus and said fixed point by means of an arm having its opposite end portions pivotably supported at said one point and said fixed point respectively, characterized in that there is provided means for detecting a sum of a rotational angle of said armabout said fixed point as the bending proceeds since the beginning of the bend ing work and an angular variation at the portion of said arm jointed to said pipe to obtain a true bend angle.

In the drawings; FIG. 1 is a schematic view showing the outline of an apparatus for precisely bending a metallic pipe,

FIG. 2 is a schematic view for representing the relation between the true bend angle and the rotational angle of the rotary shaft at the fixed point in the apparatus shown in FIG. 1.

FIG. 3 is a schematic view showing one preferred embodiment of the present invention.

As shown in FIG. 2, if the angle between the arm D and the pipe axis in the beginning of the bending work is represented by 40 the corresponding angle during the progress of the bending work is represented by 4 the rotational angle of the arm about the fixed point during this period of time is represented by 4 0,,

and the true bend angle is repregnted by L Q th en Instructed Value LII beadin Thus, one feature of the present invention exists inv ing work the true bend angle g is continuously detected by continuously detecting the 565%? 20, and (flea-I! 403!) Now the present invention will be described in connection to one preferred embodiment with reference to the accompanying drawings. I

In FIG. 3, as a pipe 4 is pushed into the bender by a pressing force P, said pipe 4 is bent in the region between a support point 1 and a press point 2 while said press point is successively advanced to the position 2', where said pipe is in the state represented by a numeral 4'. In this arrangement, in order to bend the pipe, there are provided known high frequency induction heating device 5 and a known cooling device 6 to be used after In addition, reference numeral 3 designates guide rolls, numerals 7, 7' designate a deviation detector, numeral 8 designtes a sticker to the pipe, reference C designates a fixed point outside of the pipe, and 46,,

40 40,, and 4 0 represent the same angles as thasssb an-iafifiaknmman ,g,

Although the bending itself can be attained in a simple manner through the above-described method, it is difficult to determine the true bend angle 40 of the pipe. However, since the relation of 40 40, (L05" L0 can be proved geometrically in the In the above arrangement, L0, is obtained by detecting the rotational angle of the rotary shaft at the fixed point by means of a resolver or the like, and the angle variation at the joint between the pipe and the arm represented by (L 6 L 63') is obtained by providing a detector of a rotational angle (such as a resolver) on the rotary shaft of the sticker 8 to the pipe and by setting the reading of the resolver for the initial value of 46 in the beginning of the bending work at 0. In other words, as the bending proceeds, the value of 419 114 Q11 A 03) is electrically detected and the true bend angle 4.0 is measured on the basis of said detected value. Furthermore, if the bending work is automatically (or manually) stopped when the measured true bend angle has become coincident with a preset angle, it is possible to easily obtain a required bend a le- As described, according to the present invention, the bend angle can be controlled in a precise manner, and so the corrective bending work which needs a lot of steps is not required at all in contrast to the prior art practice. I V v Through test measurements for the bending achieved by means of the above-described apparatus according to the present invention, we have obtained very favorable resultsas shown in the following table:

Actual Bend Angle I the following relation is established:

having an initially generally straight portion being bent to curved form by longitudinally moving the pipe while applying a lateral force thereto in said portion, said defecting apparatus comprising:

means establishing a first translationally fixed, angularly rotatable axis outside the pipe, laterally spaced therefrom and disposed generally in the imaginary plane normal to the longitudinal axis of the pipe at the juncture between where the pipe remains unbent and where the pipe is being bent;

means establishing a second angularly rotatable axis on the pipe in said portion whereat the bend angle with respect to the longitudinal axis of the pipe at the imaginary plane is to be determined, the second axis being parallel to the first axis;

arm meansjoining said first and second axes and being so mounted at opposite ends with respect thereto that as the pipe is longitudinally moved in being bent, one end of the arm moves angularly about the first axis in correspondence to the angular movement of the opposite end of the arm about the first axis due to the joining of said opposite end and the pipe at the second axis;

means measuring the angular movement of said arm about the first axis;

means measuring the angle between said arm and the longitudinal extent of the pipe at said second axis; and

means for detecting, as the bending proceeds, the

sum of:

a. the angular disparity between the opposite extremes of disposition of said arm due to angular movement about the first axis; and

b. the difference at said opposite extremes of dispo- 2. A method for detecting the bend angle of a pipe having an initially generally straight portion being bent to curved form by longitudinally moving the pipe while applying a lateral force thereto in said portion, said deitecting method comprising:

tying the rotational disposition of the first fixed point to the second fixed point, so that as the pipe is longitudinally moved in being bent, said first point is correspondingly angularly moved to maintain its angular position fixed relative to said second point;

as the bending proceeds, monitoring the sum of: a. the angular disparity between the opposite extremes of disposition of said first point; and

b. the difference at said opposite extremes of angular disposition of said first point of the angle between a straight line joining said first and second points and the longitudinal extent of said pipe at said second point;

as a measure of the angular disparity between the'disposition of the longitudinal axis of said pipe axially coincident with said second point, the angular amount said pipe has been bent at said second point. 

1. Apparatus for detecting the bend angle of a pipe having an initially generally straight portion being bent to curved form by longitudinally moving the pipe while applying a lateral force thereto in said portion, said defecting apparatus comprising: means establishing a first translationally fixed, angularly rotatable axis outside the pipe, laterally spaced therefrom and disposed generally in the imaginary plane normal to the longitudinal axis of the pipe at the juncture between where the pipe remains unbent and where the pipe is being bent; means establishing a second angularly rotatable axis on the pipe in said portion whereat the bend angle with respect to the longitudinal axis of the pipe at the imaginary plane is to be determined, the second axis being parallel to the first axis; arm means joining said first and second axes and being so mounted at opposite ends with respect thereto that as the pipe is longitudinally moved in being bent, one end of the arm moves angularly about the first axis in correspondence to the angular movement of the opposite end of the arm about the first axis due to the joining of said opposite end and the pipe at the second axis; means measuring the angular movement of said arm about the first axis; means measuring the angle between said arm and the longitudinal extent of the pipe at said second axis; and means for detecting, as the bending proceeds, the sum of: a. the angular disparity between the opposite extremes of disposition of said arm due to angular movement about the first axis; and b. the difference at said opposite extremes of disposition of said first axis of the angle between said arm and the longitudinal axis of the pipe at said second axis; as a measure of the angular disparity between the disposition of the longitudinal axis of said pipe axially conincident with said second axis, the angular amount said pipe has been bent at said second axis.
 2. A method for detecting the bend angle of a pipe having an initially generally straight portion being bent to curved form by longitudinally moving the pipe while applying a lateral force thereto in said portion, said detecting method comprising: establishing a first translationally fixed point outside the pipe, laterally spaced therefrom and disposed generally in the imaginary plane normal to the longitudinal axis of the pipe at the juncture between where the pipe remains unbent and where the pipe is being bent; establishing a second point fixed on the pipe in said portion, whereat the bend angle with respect to the longitudinal axis of the pipe at the imaginary plane is to be determined; tying the rotational disposition of the first fixed point to the second fixed point, so that as the pipe is longitudinally moved in being bent, said first point is correspondingly angularly moved to maintain its angular position fixed relative to said second point; as the bending proceeds, monitoring the sum of: a. the angular disparity between the opposite extremes of disposition of said first point; and b. the difference at said opposite extremes of angular disposition of said first point of the angle between a straight line joining said first and second points and the longitudinal extent of said pipe at said second point; as a measure of the angular disparity between the disposition of the longitudinal axis of said pipe axially coincident with said second point, the angular amount said pipe has been bent at said second point. 